Filament structure for electron discharge device



Jan. 20, 1953 w. N. PARKER 2,626,370

FILAMENT STRUCTURE FOR ELECTRON DISCHARGE DEVICE Filed May 26, 1949 2 SHEETS-SHEET l INVENTO M N. PAR R Jan. 20, 1953 w. N. PARKER 2,626,370

FILAMENT STRUCTURE FOR ELECTRON DISCHARGE DEVICE Filed May 26, 1949 2 SHEETS-SHEET 2 F/ 'g.4 Fly. 5

Patented Jan. 20, 1953 FILAMENT STRUCTURE FOR ELECTRON DISCHARGE DEVICE William N. Parker, Lancaster, Pa., assignor'to Radio Corporation of America, a corporation of Delaware Application May 26, 1949, SerialNo.- 95,432

13 Claims, (Cl. 313-273) The present invention relates to electron, discharge device electrode structures and more particularly to electrodes provided withmounting heads, and a method of making the same, suitable for quick detachable interlocking engagernent with the support members thereof particularly useful in electron discharge de-- vices.

It is well known that a series limitation of electrode structures results from deformation thereof during processing or operation. In the main, such deformations results from thermal expansion of the electrode and mount, and con:- structions utilized heretofore have only been partialy successful in overcoming this with the re.- sult that devices have electrode structures therein, in particular electron discharge devices, have been seriously limited in merit. The problem presented by such deformation is-aggravated as the size of the affected parts is increased, nevertheless, even in the smallest tubes it must be effectively dealt with if the maximum merit is to be obtained,

One of the specific causes of such deformation has been the manner in which electrodes heretofore have been connected to their support members. In the co-pending application of Lloyd P. Garner filed May 26, 1949, Serial Number 95,398, (now U. S. Patent. No. 2,545,184), as.- signed to the same assignee as thepresent application, there is disclosed a novel hook or clipin, type quick detachable interlocking connection between, an electrode and its support members which, subst ntially minimizes the bending forces applied to the electrode at the point or points of contact with its support members as the various parts expand and contract.

I have found that such bending forces and consequent deformation of the electrode, can be further reduced and substantially eliminated and the electrode maintained accurately and precisely positioned in accordance with my invention.

It is therefore a principal object of my invention to provide an electron discharge device having an improved electrode structure, the elements of which may expand and'contract without causing deformation of the electrode elements.

Another object of my invention is to provide an electrode mounting head having knife-edges by which the electrode may be interlocked in a quick detachable manner with its supports and which permits the electrode to rock freely about its supports without binding.

Still another object of my invention is the provision of an electrode having a mounting head 2 for quick detachable connection to the support therefor which automatically centers the electrode and maintains the same precisely located;

Yet another objectis the provision of, a method for manufacturing an electrode with amounting head having accurately formed knife-edges which eliminates tedious and difiicult machining operations and in accordance with which, the knifeedges are formed by hot-heading or punching.

In carrying my invention into effect, I prefer ably provide the mounting head of an electrode with a knife-edge bearing surface extending in a plane which intersects the axis ofjthe electrode.

The novel features that are consideredjcharacteristic of this invention are set forth with, particularity in the appended claims. The invention as well as additionalobjects and advantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which Figure 1" is an elevational" view partly insection of an electron discharge device embodying my invention;

Figure 2 is a. fragmentary, perspective view on an enlarged, scale of an electrode mounting head constructed in accordancewith my invention;

Figure 3. is a front, elevational View th reof partially in section;

Figures 4 and 5 are front elevational views partially in section of modifications thereof also constructed in accordancev with my invention;

Figurefi'is a plan view of the electrode shown in Figure 2 mounted in an annular support; and

Figure 7 is a schematic view. illustrating; the operation, of my invention.

Referring now to. the drawings wherein like reference characters denote corresponding parts to Figures 2 and 3 in particular, an electrode H] has a mounting head II provided with knifeedges l2 which seatsin a V groove, I3, formed in mounting block or support I 4 and at right angles to a slot [5 alsoformedtherein. Knifeedges I2 contact mounting block or support l4 alongline A -A whic h, preferably intersects axis B.- and. .atriehtangl here T p rmithe desired unimpeded rocking; of; electrode In; about 1ine.A-.A V groove l3; has a reater. angle than the intersecting planes forming knife-edgesv I2, I have found av knife-edge angle-of degrees and a.V groove angle of 90, degreessatisfactory although other appropriate combinations maybe used.

As will' bemore fully pointed out hereinbelow, I'form'knife-edges I-2 leaving residual radius or fillet l6. Furthermore, though slot I5 is large enough to give free clearance to electrode ID as it rocks about line A-A, it is narrow enough so as to co-act with residual radius IS on the sides of the electrode and thereby center the electrode in the slot. This prevents the electrode from moving about in the V groove and slot as the mounting block or support executes a succession of movements.

As shown in Figure 4, an electrode I! has a mounting head [8 formed with relatively large residual radii or fillets [9 while in Figure 5 electrode 20 is provided with knife-edges 2i which are not co-linear but are swept up. In both instances contact is made in two points 22, 23 respectively, and forming a straight lineintersecting the axis of the electrode; thereby avoiding having undesirable bending moments acting on the end of the electrode.

As noted hereinabove my invention is particularly useful in electron discharge devices but may also be advantageously used in electric heating furnaces or other devices. Referring to Figure 1 electron discharge device 24 is a high power tube capable of a power output of the order of 500,000 watts and forms the subject matter of my co-pending joint application with Lloyd P. Garner and Willis E. Harbaugh, filed March 17, 1949, Serial Number 81,932 (now U. S. Patent No. 2,544,664), and which is assigned to the same assignee as my present application.

Electron discharge device 24 is an internally water cooled triode having a cathode and grid, each of which comprises a circular array of axially tensioned discrete elements or bar-like sections indicated respectively at 25 and 26, surrounded by a cylindric anode 2'! and all are housed in a demountable evacuated envelope as shown.

Each of the cathode elements or sections 25 is supportedadjacent its upper ends by a laminated flexible support means indicated generally at 28 supported from central conducting tubular support member 29 which is connected to a copper diaphragm 38 by means of which it is connected electrically to terminal ring 30.

Still with reference to Figure 1, it is seen that the other or lower end of each cathode element or section 25 is inflexibly mounted in ring 3| brazed to outer cathode conducting support 32 at the lower end of a beam former array. Conducting support member 32 is coaxial and concentric-with conducting support 29 and has a lower portion of increased diameter which, below terminal ring 33, forms part of the exterior envelope of the tube. The upper portion of conducting support 32 which is in the active region of the device 24 has a plurality of grooves machined therein, one for each of the cathode sections of which there are fortyeight in the tube illustrated. Said grooves are separated by lands 34 which function as the beam former array and focus the electron stream emitted from each cathode section. It is apparent, therefore, that each cathode is flexibly mounted at one end to one conducting support member and infiexibly mounted at the other end to the other conducting support member. Further it should be noted that the conducting supports 29, 32 are rigidly connected by a mechanically strong insulating and hermetic seal Insulated from and supported on central conductor 29 is a hat shaped grid support member 35 having an annular peripheral flange at its lower extremity with slots and circular centering or cating V notches formed therein. There is one slot for each grid element 26 which are equal in number to cathode elements 25. Grid elements 26 each hook into grid support member 35 and are accurately positioned by means of the slots and V notches, as will be more fully described hereinbelow, in such manner that each grid element is opposed in close proximity to one of the lands 34 intermediate two adjacent cathode elements. Adjacent their lower ends, each grid element or section 26 is hooked or clipped into a separate flexible support means 36 which in turn are supported from grid terminal ring 31. Support members 28 and 36 are described and claimed in the co-pending application of Willis E. Harbaugh filed May 26, 1949, Serial Number 95,442 (now U. S. Patent No. 2,570,121).

The cathode, grid and. beam former arrays form closely positioned, critically spaced units with the cylindric anode. In the tube illustrated the cathode and grid elements are tungsten bars approximately 8 inches in length and extremely ductile at elevated temperatures. It is obvious that such a construction would be subject to objectionable deformation during processing and operation which would render it inoperative were the cathode and grid elements not mounted in such manner that they may freely expand and contract without undergoing deformation. Also, unless the electrodes are mounted by means of knife-edges in accordance with my invention they may be subjected to bending moments resulting in permanent deformation where the electrode supports and associated parts are of higher expansivity than the electrode. Such is the case in tube 24 since support 28 as well as conducting supports 29, 32 are copper while cathode elements 25 are tungsten bars or rods. Magnetic effects on self-heated cathode 25 may also introduce undesirable bending moments if there is any binding between the mounting head and its support.

To insure firm contact of each of the electrodes or electrode elements with its supports by way of the knife-edges, each electrode is maintained in axial tension. Two arrangements for axially tensioning each of the elements independently are utilized in electron discharge device 24. In the case of cathode elements 25 a coil spring 40 in a cylindric tube (shown by solid line in Fig. 1) is provided for each segment of flexible support 28 which acts against an insulating link 4| and which in turn engages rocker arm 42. Rocker arm 42 at one end is free to pivot in a groove in the lower arm of L-shaped ring 43 while its other end is bifurcated and engages in another V groove in the underside of mounting block 44. Coil springs 40 in their cylinders are arranged in circular array in an annular channel formed by conducting support 32 and seal 39. Grid support members 36 are each resilient and include a plurality of steel laminations which serve to maintain each grid element 26 in axial tension without any additional tensioning means.

Cathode and grid elements 25, 26 each have a mounting head H with knife-edges l2 and fillet or residual radii l6 formed at each end thereof. As most clearly seen in Figure 1 the upper cathode mounting heads are each individually mounted in separate mounting blocks 44 at the end of each segment of flexible support 28; the lower cathode mounting heads being clipped into slotted annular block 3!. The upper grid mounting heads are each clipped into an annular peripheral slotted block on support member 35 while the lower grid mounting headsare each clipped into" mounting blocks-'45 on separate resilient supports 36 whi'ch are arrangedin radia-l array.

Mountingblocks- M and 45"aresimi1ar'to block M and are-each provided-with V grooves and slots. Annular block 3|- aswell as the annular slotted block on support member 35 each are provided with an annular V groove'formed by surfaces 66 and 41 (Figure 6). As apparent in Figure 6, mountingheads- H with knife-edges l2 are particularlysuited forengaging the surfaces of the annular V groove. The knife-edges contact surfaces 46, W ati points 38, 49, 5t and 5| rather than at the bottom 52 ofthe V groove. All of the contact points 46,. All, 38- and 49- lie on line C-C"which intersects the axisttlofth'e electrode elementand forms airi'ghtangIe therewith.

The" operation" ofmy improved electrode structure may be bestunderstood from Figure 7 where the expansion and movement of one of the electrodeelements-of tube 24 is shown diagrammatically. The electrode element as shown is'mounted between fixed'supportie and flexible or movable supportfie by means of knife-edges [2 on heads H. and maintained in axial tension in a manner described hereinabove. As the electrode i'sheated and expands, movable support55 changes its position in response to force 56 required to. maintain contact by axial tension in the electrode. This new position is indicated by the broken lines. It

is seen that all necessary rocking; tilting or displacement motions may take place without introducing bending moments in the electrode.

Knife-edges l2 may be formed by machining or otherwise removing material as well known in the metal working art. However, for a refractory metal such as tungsten, it is necessary to grind away material from each of four directions and at appropriate angles to the axis of the electrode so as to form the two knife-edges. Neck-like constricted portion 5? is also formed at this time. However, I have found that the knife-edges and residual radii or fillets may be best formed by a method which includes hot-heading. First necklike constricted portions 5? are ground, machined or hot punched adjacent each end of the electrode leaving a relatively short head. This head is then held above a die shaped like block it with constricted portion 51' extending down through a closely fitting slot corresponding to slot H5. The surfaces forming the V groove in the die form an angle of 60 degrees corresponding to the intersecting surfaces of the knife-edges to be formed. The head is then heated by flame or other suitable means to a temperature of at least 1009" C. When the head has been heated it is suddenly forced down into the V groove of the die by a hammerlike punch forming knife-edges in the bottom of the V groove. A light tapping readily removes the electrode from the die. The die and punch are preferably mounted in a standard punch press to give a quick but controlled heading stroke. Since the punch and die tend to warm up appreciably due to the heat of the flame and hot work they are best made of a red-hard tool steel. The V groove may be machined in the die before hardening and the slot ground in after hardening.

Electron discharge device electrode structures made in accordance with my invention may be processed as in the case of high temperature bakeouts and operated without undergoing deformation. Such electrode structures have been found to be free of kinks or bowing due to bending moments in the mounting heads even after lon periods of operation.

' It isapparent that 1* have provided: athighly useful" device and method of manufacturing elec:- trode mounting heads which permits accurate close spacingsofelectrodes 'freefrom undesirable deforming force's: Furthermore, by providing pressure contact at predetermined. local points in accordance with my invention intermittent'contact betweerr theelectrodeand its supports is effectively eliminated. The-foregoing areparticularly' advantageous in high power or high frequency devices.

While my invention is subject'to obvious modifications by-those skilled in the art, it is intended tocover all such modifications as come within the scope of the appended claims.

I claim:

1; An electron discharge device, comprising an electrode, support means for said electrode having atleast one V groove-formed therein, and said electrodehaving a knife-edge formed thereon and quick detachably seatedinsaid groove;-

2.- An electron discharge device, comprising at least two co-acting electrodes, support means'for each of said electrodes, at least one of said electrodes being elongated and having mounting heads formed adjacent each of its ends, each of said mounting heads having a knife-edge which extends in a plane intersecting the longitudinal axis of said elongated electrode, the support means associated with said elongated electrode includingmeans axially tensioning said elongated electrode and means" having spaced V grooves formed therein adapted to receive said knifeedges, and each of said knife-edges being quick detachably seated in one of said V grooves.

3. An electrode structure, comprising an electrode having spaced apart mounting heads formed thereon, each of said mounting heads having a knife-edge formed thereon, means supporting and axially tensioning said electrode and having spaced apart V grooves formed therein, and said electrode being in quick detachable engagement with said means with said knife-edges seated in said V grooves.

4. An electrode structure, comprising an elongated electrode having mounting heads formed at each end thereof, each of said mounting heads having knife-edges extending in a plane which intersects the longitudinal axis of said electrode, means supporting and axially tensioning said electrode, said means having spaced apart slotted V grooves formed therein, said electrode extending through said slots with the knife-edges on one of said heads in one of said V grooves and the knife-edges on the other of said heads in the other of said V grooves.

5. An electrode structure as described in claim 4, wherein said slots are large enough to permit said electrode to move freely therein, said electrode has fillets formed at the points where said knife-edges merge with the longitudinally extending portion of said electrode, and said fillets each engage an edge formed at the intersection of one of said slots and grooves and maintain said electrode centrally positioned in said slots.

6. An electrode, comprising an elongated body portion having integral mounting heads formed adjacent each end thereof, and each of said heads having knife-edges facing each other and extending in a plane which intersects the longitudinal axis of said electrode.

'7. An electrode, comprising an elongated body portion having integral mounting heads formed adjacent each end thereof, and each of said heads having knife-edges facing each other and extending in a line which intersects the longitudinal axis of said electrode at right angles.

8. An electrode assembly, comprising an elongated electrode having a mounting head with a knife edge formed thereon and integral therewith, and support means for said electrode and having a slot formed therein through which said electrode extends with its knife edge in quick detachable engagement with said support means.

9. An electrode assembly, comprising an elongated electrode having a knife edge formed thereon and a portion of reduced cross section merging with said knife edge, and support means for said electrode, said knife edge being in quick detachable engagement with said support means.

10. An electrode assembly, comprising an elongated electrode having portions of reduced cross section adjacent each end thereof and knife edges formed thereon merging with each of said reduced portions, and support means having slots formed thereon through which said reduced portion-s extend with said knife edges in quick detachable engagement with said support means.

11. An electrode comprising as contiguous parts of an integral structure, an elongated element, a portion of reduced cross-section extending longitudinally from one of the ends of said element, a mounting head of larger cross-section than said portion and attached to the end thereof, two integral parts of the head on opposited sides thereof respectively extending transversely in opposite directions beyond the sides of the reduced portion, each of said two parts having a knife edge on its side toward said elongated element, each of the knife edges merging with said reduced portion, and the two knife edges lying in a common plane.

12. An electron discharge device, comprising an electrode, said electrode having a knife edge formed thereon, and conducting lead-in means only quick detachably connected to said knife edge, said electrode being solely connected to said conducting lead-in means.

13. An electron discharge device, comprising an elongated electrode having knife edges formed thereon, and conducting lead-in means for said electrode and in quick detachable engagement therewith at said knife edges.

WILLIAM N. PARKER.

REFERENCES CITED The following references are of record in the file of this patent:

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